The last few years have been boom times for the television-set manufacturing industry, with U.S. viewers rushing out to buy flat-screen TVs as the government mandated the switchover to digital broadcasting. But now that most Americans have tossed out their old cathode-ray TV sets, manufacturers are finding it tough to convince them to upgrade again, reports The New York Times.

TV makers are hawking their new sets–including 3D and Internet connections–at this week’s Consumer Electronics Show, but the sets aren’t creating enthusiasm among consumers, the story notes. Analysts and TV makers now estimate that consumers will change their sets every five to seven years, slightly longer than the three- to four-year wait to replace PCs.

The article points out that about two-thirds of U.S. homes have a flat-screen TV set, and "the laggards are stubborn," according to Paul Gagnon, director of North American TV research at DisplaySearch.